Wiring New Built-in Double Oven


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Old 03-30-23, 04:06 PM
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Wiring New Built-in Double Oven

Replacing an older 27 wall oven with a newer version of the same oven. Old oven required a 30 amp breaker and new oven also requires a 30 amp breaker. When the house was built they ran 4 wire, #6awg romex from a subpanel about 40 feet to a 50 amp receptacle behind the oven cabinet. I know that the oven unit requires hardwire. The outlet is way too low on the wall, so my plan is to use the 4x4 box as a junction box with about 5 of NM cable to a new 4x4 box located just above the oven cabinet. This is where I will connect to the cable whip that comes with the oven unit. It looks like the cable whip on the oven is #8awg. What type of wire nut should I use to join each #6awg wire to the #8awg wire? Would this be the same wire nut to connect the #8awg wires together? I will use a blank access cover on the box. The installation manual for the new oven unit specifies a 30 amp breaker for this particular oven.
 
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Old 03-30-23, 04:58 PM
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I would use 6AWG to extend the circuit to the upper box.
You can use IDEAL 454 (Blue Wing) wire nuts to join 2 #6 or 2 #8, or 1 #6 and 1 #8.
 
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Old 03-30-23, 06:41 PM
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If the oven specs a 30 amp max breaker then you really only need to use #10 wire/cable.
 
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Old 03-31-23, 06:41 AM
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The original house, 1991, was built with a single oven, not double. From what I can tell, the breaker was 50 amps and they ran #6awg to a really big three prong receptacle.. When an upgrade to double 30 amp ovens was done in 2005 they utilized the plug and connected the whip from the oven unit to with a plug. I have removed the recepticle, made it a junction point and am location a need box in the cabinet just over the oven unit. I changed the 50 amp breaker to a 30 amp years ago to to compatible with the oven specifications.
 
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Old 03-31-23, 08:10 AM
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It's probably my OCD, but I'm not crazy about the idea of having 40 feet of #6 and then 5 feet of #8 (or #10) running to a JB where the oven ties in. If down the road, someone sees the #6 in the panel and decides to swap to a 50 amp breaker again to serve a big Induction range or the like, and they don't realize that the last 5 feet aren't #6, it would be a problem. Is it likely...no, but why not use #6 for that 5 feet and avoid any possibility. It's only going to be a few bucks more.

More than once I've come across a circuit where someone added a light and used #14 to extend a circuit that has #12 and a 20 amp breaker. Sure, the light's not going to overload that section of #14, but it just seems like a bad idea. Anyway, that's why I suggested using #6 for the last 5 feet.
 
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Old 03-31-23, 08:54 AM
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I agree with the #6awg. One more question, please.
The new 4” box will be located in a cabinet just above the ovens, surface mounted. The new 5’ cable will run vertically in a wall cavity. I plan to drill a 1” hole in the back of the top cabinet and bring the cable out through the sheetrock and back of the top cabinet and make a bend to come into the side of the new 4” box. It it acceptable to have a few inches of the romex exposed inside this cabinet? If I try to come into the back of the box, so no romex is exposed, I do not think I could bend the #6awg conductors to fit into the box. There would have to be a severe bend to be able to fold them back.
 
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Old 03-31-23, 01:57 PM
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It is ok to have some of the NM jacket exposed.
When using NM cable the important thing is to make sure the cable is protected from heat and abrasion.
 
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Old 03-31-23, 02:19 PM
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Thanks for all the great help. There will only be about five to six inches of NM exposed. It is in the back of an upper cabinet.
 
 

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